Known pistons have many different shapes and configurations. In order to minimize the weight of the known pistons, they are normally made of aluminum. Other known piston assemblies may have portions made of steel and other portions made of aluminum. Likewise there are pistons assemblies made of two different parts and secured together by bolts or pins.
The pistons used in typical engines having crankshafts require a mass of material to permit the connection of the connecting rod to the piston. This mass of material not only adds weight but it also adds to the length of the piston. When using aluminum pistons, the heat that is induced into the piston during combustion is quickly conducted away by using water cooling jackets surrounding the chamber that the piston moves within.